Insulated connector and method



July 12, 1966 H. J. HIRTZER INSULATED CONNECTOR AND METHOD Filed Jan. 21, 1965 INVENTOR Henry J. Hirfzer Attorneys United States Patent 3,260,796 INSULATED CONNECTOR AND METHOD Henry J. Hirtzer, 1308 Martino Road, Lafayette, Calif. Filed Jan. 21, 1965, Ser. No. 426,827 14 Claims. (Cl. 174-178) This invention relates to an insulated connector and method and more particularly to a high voltage insulated connector capable of sustaining high tensile loading and a method for making the same.

Heretofore, insulated connectors have been available for use with cranes and other equipment to protect against high voltages. Such devices, however, have had serious defects. For example, many such devices have had unpredictable load characteristics because of unequal load distribution. For this reason such insulated connectors have had to be over-designed in order to be sure to meet the specified load requirements. This has made such insulated connectors unreasonably high in cost. There is therefore a need for new and improved high voltage insulated connector and method for making the same.

In general, it is an object of the present invention to provide an insulated connector and method which will overcome the above named disadvantages.

Another object of the invention is to provide an insulated connector of the above character in which the load bearing members are uniformly tensioned.

Another object of the invention is to provide an insulated connector of the above character which is constructed so that loading forces applied to the same are equally distributed between the load bearing members.

Another object of the invention is to provide an insulated connector of the above character which has highly predictable load characteristics.

Another object of the invention is .to provide an insulated connector of the above character which can be readily designed for specified load requirements.

Another object of the invention is to provide a method for making insulated connectors which greatly reduces the cost of manufacture of the same.

Another object of the invention is to provide a method of the above character by which the load bearing members or strands in the connector are uniformly tensioned.

Additional objects and features of the invention will appear from the following description in which the preferred embodiment is set forth in detail in conjunction with the accompanying drawing of which:

FIGURE 1 is a perspective view of a crane utilized for lifting a pipe section and incorporating in its load line an insulated connector constructed in accordance with the present invention.

FIGURE 2 is a view taken along line 22 of FIGURE 1 and shows an end view of the insulated connector.

FIGURE 3 is a longitudinal view partly in crosssection taken along the line 33 of FIGURE 2 and shows certain parts broken away.

In general, the insulated connector consists of a pair of spaced apart fittings which are provided with circumferentially spaced and radially and outwardly extending fingers having recesses formed there, and facing outwardly in a longitudinal direction. Groups of fibers are formed into strands. The strands are looped over the fingers in the recess and extend between the fingers of the fittings. A plurality of additional strands are wrapped circuinferentially around the longitudinally extending strands to equalize the tension on the strands on the fittings. A plastic resin is embedded in the strands to form the fibers into a rigid unitary solid mass for supporting the fittings in a spaced predetermined relationship.

As shown in the drawings, an insulated connector forming the present invention is shown being used in a typical installation such as on a crane 11. The crane 11 is of a conventional type and consists of a mobile Vehicle 12 having a boom mounted thereon for rotational movement of the body about a vertical axis and for raising and lowering about a horizontal axis. A plurality of load carrying cables 14 are supported by the boom 13 and are connected to a block 16. Additional cables 17 are attached to the block 16 and support a ball weight 13. Suitable means is provided for connecting the ball weight 18 to the insulated connector 10 and consists of a swivel bolt 19 which is threaded into the insulated connector 10 as hereinafter described.

In the typical application for the insulated connector shown in FIGURE 1, a pipe 21 is being carried by a chain 22 wrapped about the pipe and connected by suitable means such as a hook 23 to the insulated connector Iii. The hook 23 is threaded into the insulated connector 10 as hereinafter described. As hereinafter described the insulated connector 10 is provided to protect workmen handling the pipe 21 in case the boom 13 should strike high voltage transmission means such as high voltage lines 26 shown in FIGURE 1 of the drawing.

The construction of insulated connector It) is shown in detail in FIGURES 2 and 3 of the drawing. As shown therein, the insulated connect-or consists of a rod 27 of suitable insulating material such as cast plastic resins and a pair of fittings 28 which are mounted on the ends of the rod 27 and are supported thereby in spaced apart longitudinal relationship. The rod 27 serves to provide support for the fittings during the winding operation as hereinafter described. The fittings 28 are provided with a plurality of circumferentially spaced hook-like spokes or fingers 29 which extend radially and outwardly from an integral central cylindrical portion 31. Each of the spokes or fingers 29 is provided with a substantially U-shaped recess 30 facing outwardly in a longitudinal direction with respect to the longitudinal axis passing through the rod 27 and the two fittings 28. Each of the fittings 28 is provided with a cylindrical bore 3 2 centrally disposed within the central cylindrical portion 31. The bores 32 are coaxially aligned with respect to the longitudinal axis of the insulated connector. A portion of each of the bores 32 is provided with threads 33 which are adapted to receive a suitable connecting means such as the swivel bolt 19 and the hook 23 hereinbefore described.

A plurality of load bearing strands or elements 36 formed of a plurality of fibers of suitable insulating material such as fiber glass extend between the fittings 28 and are looped into the U-shaped recesses provided in the spokes or fingers 29 of the fittings to form the tension elements which connect the fittings 28.

In performing any method for the manufacture of the insulated connector, the following procedure is utilized. After the fittings 28 have been mounted upon the opposite elnds of the insulated rod 27, the rod 27 and fittings 28 are placed in a rotatable mandrel. Assuming that fiber glass is being used, two separate strands are taken and the ends are tied to two of the fingers 29, one on each of the fittings 28 and preferably in longitudinal alignment with each other. Prior to the time that the groups of stnands are tied to the fittings, the strands are thoroughly wetted with a suitable plastic resin such as an epoxy by passing the same through a bath of such resin. While the stnands are still wet, the ends of the two strands are tied to the fingers 29. Then the operator, with a strand in each hand, and by controlling the speed of rotation of the machine driving the mandrel with his foot, takes the two strands and passes them into the recesses 32 in the fingers 29 and back and forth between the fingers 2 so that they cross each other repeatedly at spaced circumferential points intermediate the two fittings 28 as indicated by the dashed lines 37 shown in FIGURE 3. Thus, as the mandrel is rotated, the two stnands are continuously fed through the resin bath and are passed and looped into the recesses 32. provided in the fingers. This procedure is continued for several revolutions of the fittings 28 so that there are a plurality of strands in each f the recesses and so that the strands extending longitudinally between the fittings form a circular cylinder in transverse oross-section or at right angles to the longitudinal axis of the insulated connector.

After the desired number of longitudinal strands have been placed upon the fittings 28, a second group of strands 41 is wound circumferentially about the longitudinal strands 36 and forms :a cylindrical sleeve extending longitudinally about the strands 36. This is accomplished in a suitable manner such as by utilizing the two strands which were utilized for forming the longitudinal group of strands 36 by moving the two strands to the center, and holding them there while the fittings are rotated in the mandrel to permit the strands to be wrapped about the longitudinal strands 36 as the fittings are rotated. The operator, with his hands, gradually moves the strands outwardly towards the fittings, and then back and forth until the desired number of groups of strands have been wrapped circumferentially about the longitudinal strands 36. The strands are then cut and the ends embedded in the already existing strands so that the cylindrical sleeve formed by the strands is relatively smooth.

It should be appreciated that up to this stage, all of the groups of strands are still wet, and for that reason are in a relatively fluid state. The sleeve which is for-med by the circumferential groups of strands 41 causes all of the longitudinal strands to be formed as catenaries to seek a center position which causes a uniform tension to be placed on all of the longitudinal strands 36. The size of the insulated rod 27 is such so that there is a space 39 between the strands 36 and the insulated rod 27.

it can be seen from the pattern which is utilized for the strands, that the strands overlap and cross over each other to provide a series of overlapping strands which are interwoven to give an inherent locking characteristic to the groups of strands to cause uniform distribution of the load as hereinafter described.

After the winding operation has been completed, the insulated connector is removed from the rotating mandrel and is cured in a suitable manner such as by baking the same. This causes the epoxy to be cured and causes the groups of strands to be formed into a rigid solid unitary mass.

After the curing operation has been completed, a suitable protective covering 42 is placed over the entire assembly with the exception of the extreme ends of the fittings 223. This cover 42 can be formed of a suitable insulating material such as plastic. It is preferable that the plastic be one which can be introduced to all the voids within the insulating coupling, as for example, the voids or spaces 39 between the strands 36 and the insulated rod 27 as shown in FIGURE 3 of the drawings.

By way of example, one insulated connector constructed in accordance with the foregoing method utilized glass fibers having a diameter of approximately three ten thousandths of an inch and in which approximately sixty thousand fibers of this diameter were grouped together to form each of the strands utilized in the longitudinal strands as and the circumferential strands 41.

In utilizing this design, it has been found that it is relatively easy to calculate the load bearing characteristics of the insulated connector. This can be readily computed by calculating the cross-sectional area of the strands passing through the U-shaped recesses provided in the fingers 29. The recesses 32 serve as excellent load supporting surfaces and since any loading placed on the connector is equally distributed between the longitudinal strands 36, the tensile strength of the connector can be readily calculated. Calculations are also relatively easy to make because the longitudinal strands 36 are always in pure tension. In view of this fact, it is not necessary to overdesign the coupling in order to be sure to have the desired load characteristics.

It has been found that the use of the criss-oross weave of the longitudinal strands is particularly desirable because the cross-over points 38 form points at which the loading is distributed laterally from one strand to the adjacent strands. Thus, this feature also ensures that the load will be uniformly distributed among the longitudinal strands. The formation of the longitudinal strands into catenaries causes the longitudinal loading on the connector to be transformed into pure tension on the longitudinal strands to thereby give the connector its greatest load carrying capability.

From the construction of the insulated connector, it can be seen that the insulated connector can be used in any application where it is desired to insulate against high voltage. in addition, because of the design of the insulated connector, it can be made relatively small to give the desired protection against high voltage while still retaining very large load carrying capabilities.

I claim:

1. In an insulated conductor capable of sustaining a high tensile load, a pair of spaced fittings, said fittings having a plurality of circumterentially spaced, radially and outwardly extending fingers having substantially U- shaped recesses formed therein facing outwardly in a direction substantially parallel to the longitudinal axis extending between the fittings, a plurality of fibers of insulating material formed into strands, the strands extending longitudinally between the fittings and being looped into the recesses, said longitudinal strands forming a substantially solid mass in cross-section, and a plastic resin forming said fibers into a rigid solid unitary mass.

2. An insulated connector as in claim it together with a plurality of additional strands Wrapped circumferentially about said longitudinal strands to equalize the tensile forces applied to the strands when the connector is placed under tensile stress.

3. An insulated connector as in claim 2 together with a rigid rod of insulating material secured to said fittings and disposed within said strands, said rod having an exterior dimension smaller than the interior dimension of said strands to thereby leave an annular space about the inside of said longitudinal strands.

4. An insulated connector as in claim 1 wherein said longitudinal strands cross over each other at points substantially intermediate the fittings and in which said plastic resin bonds the strands together at the crossover points.

5. In an insulated connector, a pair of spaced fittings, a plurality of fibers of insulating material formed into strands, said strands extending longitudinally between said fittings and being secured to said fittings, said strands being arranged on said fittings so that they form a substantially circular cylinder in the cross-section at right angles to the longitudinal axis extending through the fittings, said connector being formed so that there is a substantially annular space extending between said fittings and inwardly from said strands forming said cylinder, and additional strands of insulating material wrapped circumferentially about the strands and extending longitudinally of the fittings to cause the longitudinal strands to be tensioned substantially uniformly whereby tensile loading applied to the insulated connector is uniformly distributed on the longitudinal strands.

6. A connector as in claim 5 wherein said strands are impregnated with a plastic resin which has been cured to form the strands into a rigid solid unitary mass.

'7. An insulated connector as in claim 5 together with a rigid rod of insulating material secured to the fittings and disposed within the strands.

8. An insulated connector as in claim 5 wherein said fittings are provided with a plurality circumferentially spaced, radially and outwardly extending fingers having U-shaped recesses formed therein and wherein the longitudinal strands extend between the fingers and are looped into the recesses formed in the fingers.

9. An insulated connector as in claim 5 together with a protective covering overlying said strands.

10. An insulated connector as in claim 5 wherein said strands cross over each other at points intermediate the fittings.

11. In an insulated connector, a rigid rod of insulating material, a pair of spaced fittings mounted on opposite ends of said rod, each of said fittings having a plurality of eircumferentially spaced, radially and outwardly extending fingers having U-shaped recesses formed therein facing in an outward direction parallel to the longitudinal axis of the insulating rod, a plurality of fibers of insulating material formed into strands, said strands extending longitudinally between the fingers and being disposed in the recesses to form a cylinder circular in cross-section at right angles to the longitudinal axis and spaced from said insulating rod, said longitudinal strands crossing over each other at points intermediate the fittings, at least one strand of insulating material wound circumferentially around said longitudinal strands for equalizing the tension on the longitudinal strands whereby when the insulated connector is placed under tension stress, the loading is uniformly distributed over the longitudinal strands, a cured plastic resin embedded among said strands and forming said strands into a rigid solid unitary mass and bonding the strands together at the cross over points, and a protective covering enclosing said strands.

12. In a method for manufacturing an insulated connector, utilizing a rigid insulating rod having spaced fittings mounted on opposite ends thereof and in which each of the fittings is provided with a plurality of circumferentially spaced, radially and outwardly extending fingers having U-shaped recesses therein facing outwardly in a direction parallel to the longitudinal axis of the insulating rod, the steps of forming a plurality of fibers of insulating material into a strand, impregnating the strand with a plastic resin, placing the strand on the fittings so that the strand extends longitudinally between the fittings and is looped into the recesses in the fittings so that the strand forms a substantially circular cylinder in cross-section at right angles to the longitudinal axis extending between the fittings and so that an annular space is formed within the cylinder formed by the strand, and wrapping an additional strand about the longitudinal strands to equalize the tension placed on the longitudinal strands.

13. A method as in claim 13 together with the steps of curing the plastic resin so that the strands are formed into a rigid solid unitary mass and placing a protective covering over the strands.

14. In a method for manufacturing an insulated connector of the type having an insulating rod with a pair of spaced fittings mounted on opposite ends thereof and in which the fittings have a plurality of circumferentially spaced, radially and outwardly extending fingers having U-shaped recesses therein facing in an outwardly direction parallel to the longitudinal axis of-the insulating rod, the method comprising forming a plurality of fibers of insulating material into two strands, impregnating the strands with a plastic resin, securing one end of each of the two strands to opposite fittings, causing the fittings to rotate and passing the two strands back and forth longitudinally between the fittings so that they overlap and cross each other and looping them into the recesses provided in the fingers to form a cylinder circular in cross-section at right angles to the longitudinal axis and spaced from the insulating rod, wrapping an additional strand impregna ted with a plastic resin about the longitudinal strands, and curing the plastic resin to form the strands into a rigid solid unitary mass.

References Cited by the Examiner UNITED STATES PATENTS 2,285,964 6/1942 Grosse 174-30 X 2,615,954 10/1952 Mungovan et a1. 2915S1.52 X 2,970,186 1/1961 Von Platen 17430' X 2,997,529 8/1961 Fink 174-138 3,024,302 3/1962 Coggeshall 174177 LARAMIE E. ASKIN, Primary Examiner. 

1. IN AN INSULATED CONDUCOTR CAPABLE OF SUSTAINING A HIGH TENSILE LOAD, A PAIR OF SPACED FITTINGS, SAID FITTINGS HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED, RADIALLY AND OUTWARDLY EXTENDING FINGERS HAVING SUBSTANTIALLY USHAPED RECESSES FORMED THEREIN FACING OUTWARDLY IN A DIRECTION SUBSTANTIALLY PARALLEL TO THE LONGITUDINAL AXIS EXTENDING BETWEEN THE FITTINGS, A PLURALITY OF FIBERS OF INSULATING MATERIAL FORMED INTO STRANDS, THE STRANDS EXTENDING LONGITUDINALLY BETWEEN THE FITTINGS AND BEING LOOPED INTO THE RECESSES, SAID LONGITUDINAL STRANDS FORMING A SUBSTANTIALLY SOLID MASS IN CROSS-SECTION, AND A PLASTIC RESIN FORMING SAID FIBERS INTO A RIGID SOLID UNITARY MASS. 